Sound box



Jan. 23, I923. 1,443,.2 74

H- Y. PRENDERGAST.

' SOUND Box. FILED MAY 11, 1922.

glwuozntox I 1 attozn u Patented Jan. 23, 1923.

tenant HAROLD Y. rnnnnnnens'r,

or BBOOKLYN, new xonx.

sounn BOX;

Application filed May 11,

To all whom it may concern:

Be it known that I, HAROLD Y. Pnnivonn- GAST, a citizen of the United States of America, residin at Brooklyn, in the county of Kings andtate of New York, have invented certain new and useful Improvements in Sound Boxes, of which the following is a specification;

This invention relates to sound boxes of that type wherein a sounding board is interposed between the diaphragm and tone arm, and is directed to providing a yielding pressure means, whereby the diaphragm is held against undue vibration. i

The improvement is directed particularly to providing a simple means for holding the sounding board normally under tension involving a tubular projection from the cover of the sound box and a sleeve member having sliding cooperation with the projection, the sleevemember having a flange between which and the cover there is arranged an expansible spring, coiled about the sleeve and tubular projection. This construction provides forholding the sounding board.

- under such tension that it is responsive to vibrations of the diaphragm in its sound amplifying efiect, and with thespecific construction provided, it is not absolutely essential that the sounding board be of an inherently resilient nature.

The invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a sectional view through a sound The diaphragm in this instance is preferably of less diameter than the interior of the casing, there being a gasket 4: interposed between the diaphragm and seat, a filling gasket 5 arranged beyond the edge of the diaphragm, and a gasket 6 overlying the edge of the diaphragm and the gasket 5.

A sounding board 7 is loosely arranged within the casing and is formed with a central sound opening 8. The peripheral edge of the soundingboard is formed in a return bend to present a narrowannular section 9,

1922. Serial No. 560,124.

integral of course with the sounding board, the free edge of which rests inwardly ot' the free edge of the diaphragm 3, so that with pressure on the sounding board, the edge of said board bears, through the intermediate gasket 6, on the edge of the diaphragm to secure the necessary holding effect of the diaphragm edge.

It is to be particularly noted that the diaphragm is of less diameter than the interior of the casing, and that the edge of the sounding board rests on the diaphragm, through the intervening gasket, very close to the extreme edge of the diaphragm. The diaphragm is thus secured in a manner to provide an'extreme sensitiveness thereof in vibration, as such diaphragm is only held at the extreme edge by the sounding board.

The sounding board of thisinvention is held in position for the purposes of amplitying or concentrating the sound waves and p at the same time securing the diaphragm in place, by a resilient compensating means, of a simple nature. For this purpose, thecover of the sound box, as 10, is formed with the usual sound outlet 11, and on the inner side with an integral sleeve 12 concentric with the outlet. This sleeve is of less length than the normal distance between the 'cover sleeve and collar without touching either and bear between the cover and annular projection 14:. The spring is normally of such length that when the cover is in position, the end of the collar. is bearing upon the sounding board, and the spring is under decided compression. V

Thus the sounding board and diaphragm are held in place solely through the medium of the spring when the coveris applied.

Claims:

1. A sound box having a sounding board, a cover, and resilient holding means between said cover and sound box, said holding means including a spring and a freely movable collar operated by said spring and bearing on the sounding board.

2. A sound box, a diphi'agm therein, a sounding board having an inturned edge to bear upon the extreme edge of the diphragm, a cover for the soundbox, and resilient holding means between said cover and sounding board, said holding means including a spring and a freely movable collar operated by said spring and hearing on the sounding ooard'. c 3.41 SOJKl hon having a sounding board and formed with a Wall outlet sound passage a collar freely slidahleon said Wall 

